在进行查询的时候偶尔会忘记加索引，下面根据mybatis的拦截器简单实现了一个索引检测工具，它会根据给定的sql查询出可用的索引及实际使用的索引，可以将其集成在junit里使用。记得在项目mybatis文件配置这个拦截器:

<plugins>
        <plugin interceptor="test.jd.paipai.common.junit.slowSql.CheckSlowSqlInterceptor" />
    </plugins>

import org.apache.commons.lang3.StringUtils;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.type.TypeHandlerRegistry;

import java.sql.*;
import java.util.List;
import java.util.Properties;

/**
 * @Author:weilu
 * @Date: 2018/12/25 10:03
 * 对执行的sql进行拦截并作索引分析处理
 */
@Intercepts({@Signature(type = Executor.class,method = "query",args={MappedStatement.class,Object.class, RowBounds.class, ResultHandler.class}),
             @Signature(type=Executor.class,method = "update",args={MappedStatement.class,Object.class}) })
public class CheckSlowSqlInterceptor implements Interceptor {

    private final static String DESC = "DESC ";

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        System.out.println("intercept start----------");
        MappedStatement statement = (MappedStatement)invocation.getArgs()[0];
        Object parameter = null;
        if(invocation.getArgs().length > 1){
            parameter = invocation.getArgs()[1];
        }
        BoundSql boundSql = statement.getBoundSql(parameter);
        Connection connection = statement.getConfiguration().getEnvironment().getDataSource().getConnection();
        Configuration configuration = statement.getConfiguration();

        String sql = getSql(configuration, boundSql);
        System.out.println("要执行的sql:"+sql);
        explainSql(connection,sql);
        //showProfiles(connection);
        Object returnValue = null;
        returnValue = invocation.proceed();

        return returnValue;
    }

    /**
     * 获取执行的sql
     * @param configuration
     * @param boundSql
     * @return
     */
    private static String getSql(Configuration configuration, BoundSql boundSql) {
        String sql = showSql(configuration, boundSql);
        StringBuilder str = new StringBuilder();
        str.append(sql);
        return str.toString();
    }

    /**
     * 获取执行的sql，取参数
     * @param configuration
     * @param boundSql
     * @return
     */
    private static String showSql(Configuration configuration, BoundSql boundSql) {
        Object parameterObject = boundSql.getParameterObject();
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        String sql = boundSql.getSql().replaceAll("[\\s]+", " ");
        if (parameterMappings.size() > 0 && parameterObject != null) {
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
            if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
                sql = sql.replaceFirst("\\?", getParameterValue(parameterObject));

            } else {
                MetaObject metaObject = configuration.newMetaObject(parameterObject);
                for (ParameterMapping parameterMapping : parameterMappings) {
                    String propertyName = parameterMapping.getProperty();
                    if (metaObject.hasGetter(propertyName)) {
                        Object obj = metaObject.getValue(propertyName);
                        sql = sql.replaceFirst("\\?", getParameterValue(obj));
                    } else if (boundSql.hasAdditionalParameter(propertyName)) {
                        Object obj = boundSql.getAdditionalParameter(propertyName);
                        sql = sql.replaceFirst("\\?", getParameterValue(obj));
                    }
                }
            }
        }
        return sql;
    }

    /**
     *  获取参数信息
     * @param obj
     * @return
     */
    private static String getParameterValue(Object obj) {
        String value = null;
        if (obj instanceof String) {
            value = "'" + obj.toString() + "'";
        } else if (obj instanceof Date) {
                //DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);
                //value = "'" + formatter.format(new Date(System.currentTimeMillis())) + "'";
        } else {
            if (obj != null) {
                value = obj.toString();
            } else {
                value = "";
            }

        }
        return value;
    }


    /**
     * 获取执行sql的索引
     * @param connection
     * @param sql
     */
    private void explainSql(Connection connection,String sql){
        try {
            Statement statement = connection.createStatement();
            String desc_sql = DESC + sql;
            ResultSet result = statement.executeQuery(desc_sql);
            if(result != null && result.next()){
                String possibleKey = result.getString("possible_keys");
                String key = result.getString("key");
                String type = result.getString("type");
                String extra = result.getString("extra");
                System.out.println("可以用到的索引:"+possibleKey);
                System.out.println("实际使用的索引:"+key);
                System.out.println("extra信息:"+extra);
                System.out.println("type信息:"+type);

                if(StringUtils.isNotBlank(possibleKey)){
                  if(StringUtils.isBlank(key)){
                      System.out.println("未使用的索引:"+possibleKey);
                  }else{
                      System.out.println("已使用索引:"+key);
                  }
                }else{
                    System.out.println("没可使用的索引");
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private void showProfiles(Connection connection){
        String profile = "SHOW PROFILES";
        try {
            Statement statement = connection.createStatement();
            ResultSet result = statement.executeQuery(profile);
            if(result != null){
                String Query_ID = result.getString("Query_ID");
                String Duration = result.getString("Duration");
                String Query = result.getString("Query");
                System.out.println("Query_ID:"+Query_ID);
                System.out.println("Duration:"+Duration);
                System.out.println("Query:"+Query);


            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    @Override
    public void setProperties(Properties properties) {

    }
}